Abstract: The larger of the two flanges in a grommet contains a tip portion that extends back toward the other tapered flange and overlies the circumferential slot between the two flanges to define a grommet having application to panels of a variety of thicknesses. The tip portion elastically bends, upon installing the grommet in a panel, responsive to force exerted by a side wall of the panel. It exerts an elastic reaction force pressing on a side of the panel. Concurrently it pulls the other tapered flange into contact with the opposed surface of the panel through elastic force exerted through the grommets midsection. This seals the flanges against the panel's sides, notwithstanding a circumferential slot width greater than the panel's thickness and notwithstanding a panel mounting hole having a greater diameter than the bottom surface of that slot. A fire resistant layer is integrally formed or applied in that outer surface of the grommet containing the larger flange.